Linings for pipelines and passageways

ABSTRACT

The invention provides that flexible lining tubes for application to underground pipelines and passageways comprise absorbent material which is impregnated with curable synthetic resin which can be cured when the tube is placed on the pipeline or passageway surface so that a rigid pipe within the pipe is formed. The curing of the resin is controlled by filling the curing agent into micropores or microporous particles which are dispersed throughout the resin. The curing agent is only released when the resin is subjected to applied energy such as sonic and/or heat energy. A preferred method is to include CURIE temperature magnetic particles in the resin and to excite (and thus heat) the magnetic particles by applying an alternating high frequency magnetic field. The heat from the magnetic particles opens the microporous particles and causes desorbence of the curing agent and then cure of the resin. The invention also provides that the curing agent is absorbed into the absorbent layer in the first place using sonic energy.

BACKGROUND OF THE INVENTION

This invention relates generally to tubular linings for pipelines orpassageways which linings are of a type known as `softlinings` or `curedin place` linings which employ resin absorbent material which isimpregnated with curable resin which has been conditioned in order thatit may be cured to produce a pipe on the surface of the pipeline orpassageway (typically an underground sewer) thereby in effect forming apipe within a pipe.

The lining to which the invention relates is a resin absorbent tubularstructure (herein the "lining tube or pipe") which is to be used forlining an underground pipeline or passageway such as a sewer. In suchutilization, which is now practiced widely throughout the world, theimpregnated lining tube is inflated (by gas such as air, steam and/orliquid such as water) against the pipeline or passway surface whilst theresin is uncured, and whilst the lining tube is so held in position, theresin is allowed or caused to cure whereby the cured resin with theabsorbent tubular structure embedded therein forms a self supportingrigid pipe, which may or may not bond to the pipeline or passagewaywall. The purpose of this operation is to rehabilitate and/or repair thepassageway or pipeline. A particular advantage of the provision of aself supporting rigid pipe is that bonding to the existing pipeline isnot necessary, as is the case with some lining systems but it is to bementioned that this invention can be applied to pipelining systems wherethe impregnated tube does bond to the existing pipeline or passageway,such systems being those wherein the lining tube is of relatively smallthickness e.g. 5 mm or less and the resin acts like a bonding mediumrather than an impregnating medium.

Also the lining tube when the resin is in the uncured state may notstrictly be a tube in that it may be a web folded into tubular form sothat its edges overlap and such edges become fused or held relativelytogether only when curing in place has been effected. In fact, thisarrangement provides the advantage that the overlapping edges can sliprelatively as the tube is being inflated so that the tube will best fitto the passageway surface.

Examples of methods of lining of underground pipelines and passagewaysusing impregnated lining tubes which are cured in place are contained inmany patent specifications of which examples are U.K. Patent No.1,340,068, which is the original patent for this technology, and U.K.Patent No. 1,449,445.

All or by far the majority of the methods which are practised throughoutthe world using cured in place lining tubes for lining undergroundpipelines and passageways simply use a heat curable resin (e.g.polyester and heat for the curing of the resin, the application of heatcausing a catalyst and/or promoter (accelerator) in the resin to releasefree radicals and commence cross linking of the resin molecules andcrystal formation; the curing reaction is exothermic and heat isinternally generated and the curing process accelerates.

One disadvantage of this arrangement is that even if heat is not appliedto the impregnated lining tube, under ambient conditions the resin willeventually cure in a matter of days and of course if curing takes placebefore the lining tube is in place on the passageway of pipelinesurface, the lining tube is completely lost and must be scrapped. Thiscan represent a considerable loss if not a complete loss of profit on acontract. Should the lining tube cure when it is part way inside thepipeline or passageway, then the consequences financially could bedisastrous for the contractor. In order to avoid the problem of theresin curing too soon, i.e. before the lining tube is in place,contractors have resorted to extensive measures, in particular tokeeping the impregnated tube refrigerated until it is to be used onsite. This means that the tubes must be delivered to the site inrefrigerated vehicles.

The effect of this procedure is that the contractor is limited in termsof when he can mix the resin and impregnate the lining tube.

Ironically, however, once the tubes have been put in place, it isdesireable that the resin should be cured as fast as possible, as thesooner the resin cures, the sooner the contractor can leave the site. Itis to be noted that the contractor will often be given or will oftenquote a relatively short time for completion of the work, usuallyundertaken during the night. It is very important therefore that thework be completed in the shortest possible time, especially in thesecases where the performance of the work involves the renderinginoperative (as it does in many cases) of a sewage system or theblocking or obstructing of traffic.

To perform the contract therefore the contractor must on the one handhave a factory or plant at which the tube is impregnated, a vehicle forkeeping the impregnated tube refrigerated and a vehicle with a heatingmeans for heating the fluid which inflates the tube when in place, inorder to effect the curing of the resin, as well as the necessaryequipment for putting the tube into place.

There is also the dilemma concerning the resin. On the one hand it isdesireable that it should have as long a shelf life as possible to givethe contractor plenty of time to place the tube in the pipeline orpassageway before curing. On the other hand, when the tube is in place,it is desireable that curing should take place as quickly as possible.Unfortunately this dilemma has proved so far to be insoluble as theadditives such as retarders for the resin which can increase shelf lifeof the resin also increase the cure time of the resin.

Consequently, when a contractor has to perform a contract, he must havethe lining tube manufactured, and, immediately before he is to insertthe lining tube, he impregnates the tube with the resin, transports itto site (which may be remotely located) as quickly as possible, andinserts the lining tube and cures it as quickly as possible. As soon asthe resin is mixed with its catalyst for impregnation of the liningtube, there is a time countdown, and the contractor is racing againsttime.

The industry is aware of this problem and some attempts have been madeto solve it by developing special resins which are `quiescent` or`latent` and do not cure for a long time until activated by someexternal source which are examples of resins curable by light radiation,such as are disclosed in European Patent Specification No 0007086, andmethods of cured in place lining with impregnated lining tubes usinglight radiation are disclosed in U.S. Pat. No. 4,581,247 and 4,680,066.

Light radiation curable resins however include catalysts which areactivatable by the suns rays and therefore the impregnated lining tubesmust be contained in opaque wrappings during storage and transportationto avoid premature curing.

Light radiation curable resin does however have the advantage thatcuring of same can be controlled and theoretically the resin has aninfinite shelf life. When it comes to curing the in place impregnatedtube however, problems arise. Thus, special ultra violet light sourcesare needed to cure the resin; and when, as is often the case, theinflating medium is water, that water may be dirty in which case lightcuring cannot be performed. When the flowing liquid in the pipeline orpassageway is opaque, as sewage is, it must be diverted and the use oflight curing equipment suffers from the same disadvantage in thisrespect as heating-methods. For these reasons, in practice, light curingof in place impregnated lining tubes has not been successful and has notreplaced the traditional heating methods.

The invention the subject of International Patent Application No.PCT/GB93/00107, of which I am joint inventor, seeks to provide latentcurable resin systems for the production of rigid articles wherein theresin can be cured readily and quickly, but retains a long to infiniteshelf life (e.g. one year or more) making it particularly suitable foruse in cured in place lining systems for pipelines and passageways.

According to the invention the subject of said International Applicationin its most general aspect the resin includes or is located adjacentinert matter which is not affected by ambient conditions such as ambientheat and light, but such matter is susceptible to applied radiation tosuch an extent to cause curing or commencement of curing of the resin.

There are various forms which the said matter can take, and such formscan be used singly or in combination.

In one specific example, the matter comprises microencapsulation shellsin which is contained a catalyst for the resin, or a promoter(accelerator) or both, the shells being susceptible to the ultrasonicradiation to rupture the cells to release the catalyst/promoter, andhence cause commencement of the cure.

Difficulties with the use of means capable containingcatalysts/accelerators have been encountered. Thus, it is difficult toproduce the micro-capsules. Secondly, it is difficult to producemicro-capsules of sufficiently small size so that they willsatisfactorily be spread throughout the absorbent material of thelining. Thirdly, it is not easy always to rupture the micro-capsules torelease the resin and if rupture is not even and homogenous, cure can beuneven, which is highly undersirable.

The said International application also describes the use ofindividually heatable particles (iron particles) in the resin, but thedifficulty with this concept is that it requires the use of anelectrical induction source of high frequency inside the pipeline whichmay be full of water, and the problems associated therewith have notbeen solved.

The present invention has as its object to provide a lining tubeimpregnated with a latent resin system which can be selectivelyactivated for the cure of same more predictably and normally quickerthan the known proposals.

According to the present invention there is provided a lining tubecomprising an absorbent layer impregnated with a resin system whichcomprises a resin matrix and a catalyst and/or an accelerator,characterised in that the catalyst and/or accelerator is absorbent inmicro pores of microporous particles distributed throughout the resinmatrix.

By having the catalyst and/or the accelerator absorbed in the microporesof the particles, as opposed to contained in shells of microcapsules,considerable advantages are obtained including that the catalyst and/oraccelerator can be released into the resin matrix much lesser than inthe case of replacing the microshells. For example, the application ofheat has been found to cause opening of the pores of the microporousparticles and quick release of the contained substance which leads torapid and even cure of the resin matrix, which is important in theapplication of lining underground sewers.

The release of the contained substance can also be achieved by theapplication of ultrasonic energy, which achieves opening of the saidpores by the mechanical and heat energy generated in the resin matrix,and ultrasonic energy can readily be passed through liquid especiallywater and there is no difficulty in using such energy inside anunderground pipe.

Again, it is possible to include in the resin matrix cure enhancingparticles of a material which is susceptable to the electromagneticvariation of an alternating magnetic field and will heat up due to eddycurrent and hysteresis losses. The heat guaranteed by such particles canbe used for the opening of the pores of the absorbent particles.

Microporous particles as used in the invention will have a maximum sizehaving agreed to the fact that they must be dispersed throughout a resinabsorbent material, such as a fabric, typically a needled felt and inthis connection the particles would be unlikely to exceed 100μ in size.They would more likely be in the range up to maximum of 15μ to 20μ andoptimally we would prefer that the particles be in the size range 7μ to15μ. It is appreciated that in any mass of particles, there will be aparticle size distribution and some particles will be of a size abovethe range whilst others will be of a size below the range.

The micro porous particles may comprise clay particles and the clayparticles may be arranged in two groups, one of which has a catalystadsorbed therein, whilst the other group has the promoter adsorbedtherein. When the resin matrix is a polyester resin the catalystpreferably is Dibenzoyl Peroxide, and the promoter is an amine. In suchcase, the clay of said one group preferably is different from the clayof the other group.

Clay particles are made up of micro platelets having micro porestherebetween which form the pores into which the catalyst and/orpromoter is absorbed. In tests carried out it has been found that onusing clay particles supplied by In Porte under the description FULMONTXMP4 of particle size normally 20μ the clay particles absorbed thecatalyst Benzoyl Peroxide to an extent that up to 60% of the finalparticle weight comprised the Benzoyl Peroxide. Also clay particlessupplied by In Porte under designation CP639 of nominal particle size15μ absorbed the amino accelerator diethyl aniline to an extent to form30% of the weight of the final particle.

Using these "filled" microforms particles in a resin matrix of polyesterCrystic 397 supplied by Scott Bader and subjecting it to ultrasonicenergy as explained in more detail herein provided an effective resincure.

The catalyst and the promotor were absorbed into the clays by the use ofultra sonic energy. It is believed that this energy drives the moleculesof the catalyst and the accelerator into the micropores of the particlesand to achieve this the catalyst and accelerator should have a molecularsize (as indicated by molecular weight) to enable this to take place.The molecular weight of each of Benzoyl Peroxide and diethyl aniline asapprox 100μ and is sufficiently small so that the molecules thereof canbe driven into the fores of the particles.

The concept of driving catalyst and/or accelerator into the pores of themicroporous particles is an important ancillary feature of the inventionand also is an independent invention.

The Polyester resin matrix on the other hand has a molecular weight inthe order of 10,000 and therefore when the mixture of resin matrix andmicroporous particles is subsequently subjected to ultrasonic energy theresin molecules will not enter the pores but will bombard themicroporous particles, releasing the absorbent catalyst and/oraccelerator providing a rapid and even cure.

The particles of clay it should be mentioned are held together to formthe particles by electrostatic action, and the aforesaid bombardmentalso generates heat. Heat has a thermo electric effect which destroysthe electrostatic attraction between the platelets so that the poresopen and this enhances the effect of release of the catalyst and/oraccelerator so that curing takes place evenly and rapidly.

Instead of applying ultrasonic energy to release the catalyst and/oraccelerator, heat may be applied by other means to produce the sameeffect. Thus, heat may be applied in the conventional way using hotwater, hot gas or steam.

Another method involves embodying in the resin along with themicroporous particles additional particles which can be heated byapplied radiation, such as ferromagnetic particles, especially ferriteparticles having a CURIE temperature. When such particles are heated bysuch radiation, the heat in the additional particles provides the sameeffect as described above for the release of the catalyst and/oraccelerator and rapid and even core of resin matrix.

In a modification the said additional particles may form the imperviousparticles, if they are of the appropriate structures having pores forthe absorbing of the catalyst and/or accelerator. In such case, theinductive heating of the particles should provide even further releaseof the catalyst and/or accelerator, and more rapid cure of the resinmatrix.

To enhance the release of the catalyst and promoter when the resin andmicroporous particles are subjected to the energy to release thecatalyst and promoter, the resin may include the additivehexametaphosphate which functions to release the catalyst and promoterat an accelerated rate.

When an ultrasonic generator is used to release the catalyst and/orpromoter, the ultrasonic generator described in International PatentApplication No PCT/GB93/00107 or in U.S. Pat. No. 5,200,666 may be used.

As stated herein it has been found that the use of ultrasonic energy canachieve impregnation of various materials into others and as applied tothe lining of underground pipelines and passageways as discussed above,a curing agent can be caused to be absorbed into the pores of microporous particles and also that the particles themselves can be caused tobe absorbed in an absorbent lining material.

According to the present invention therefore in another aspect, a firstmaterial is caused to impregnate a second material by the application ofsonic energy to the materials when in close proximity.

In one example, where a resin curing agent in liquid form is mixed withmicroporous particles, and sonic energy is applied thereto it has beenfound that the curing agent is absorbed into the particles. The amountof curing agent which is taken up by the particles depends upon thelevel of and length of time of application of the sonic energy but goodresults have been obtained using Benzoyl Peroxide as the curing agentand Bentonite of average particle size of 5 micron.

It has also been discovered that the particles, such as the microporousparticles mentioned above, with or without the Benzoyl Peroxide adsorbedtherein, can be caused to impregnate textile sheets such as the feltsheets used to provide the absorbent materials of underground pipelinings, by the application of sonic energy. Thus, if the particles arecarried in a liquid in suspension, and a piece of the felt is immersedin the suspension and an ultrasonic probe is inserted therein anddriven, the particles are observed to move into the spaces betweenfibers of the felt, thereby to impregnate the felt which, as explainedhereinafter is of considerable advantage in the field of liningpipelines and passageways in which we are particularly interested.

In order to illustrate the various aspects of the invention referencewill now be made, by way of example, with reference to the accompanyingdiagrammatic drawings, wherein:

FIG. 1A is an enlarged view of a typical microporous clay particle;

FIG. 1B is a view of the particle of FIG. 3A when it contains a resincuring agent (catalyst or accelerator);

FIG. 1C is a view of the particles of FIG. 3A as it releases its curingagent;

FIG. 2 is a graph showing the release of curing agent from the particlesunder various conditions;

FIG. 3 is a graph showing the release of curing agent under variousconditions and when the a resin is modified;

FIG. 4 is a sectional side elevation showing a lining operation inprogress, the operation being for the application of a flexible liningtube according to the invention to an underground passage;

FIG. 5 is an enlarged sectional elevation of the lining tube which isadopted for the process of FIG. 1; and

FIG. 6 is a perspective view illustrating how the lining tube is evertedinto position in the pipeline or passageway.

The present invention in one embodiment makes major use of sonic energy,ultrasonic or audible energy, to achieve impregnation. In a specificexample, the area of application as indicated herein relates to thelining of pipelines and passageways wherein a lining tube is impregnatedwith a curable synthetic resin which remains uncured until steps aretaken to initiate the cure. Specifically, in the examples hereindescribed, micro porous particles are embedded in the lining material.These particles have absorbed therein the curing agent for the resin sothat when the lining subsequently is subjected to sonic energyespecially ultrasonic energy the curing agent which is absorbed in theparticles as released into the surrounding resin matrix effectinginitiation at least of the cure of the resin. Specifically, the materialwhich is released from the particles will be sufficient to effectcomplete cure of the resin.

Again, with specific reference to the lining of underground pipelinesand passageways, a suitable absorbent material for the lining is needledfelt comprising polyester or the like fibres. Other materials can ofcourse be used. As disclosed in the said UK patent 1449445, the felt issaturated with so as to become impregnated with the resin and in theexamples of the present invention, that resin will also contain themicro porous particles so that the particles will be distributedthroughout the lining. The particles can be introduced into the liningin one of two methods. The particles can either be caused to impregnatethe felt before the resin matrix is added, or the particles can be mixedwith the matrix and then the mixture of matrix and particles used toimpregnate the felt. In the first case, the impregnation of the feltwith the particles will be referred to as a "dry" impregnation process(although liquids are used) and in the other case where the resin mixedwith the particles is used to impregnate the felt, this will be referredto as the "wet" impregnation process.

In order to effect either the dry or the wet impregnation process it isnecessary to introduce the resin curing agent into the micro porousparticles. Specifically, tests have been carried out using micro porousparticles of a clay material (as specified hereinbefore) and the curingagent which is used so as to be absorbed into these particles isDibenzoyl Peroxide and according to this invention ultrasonic energy isused to effect the absorption of the Benzoyl Peroxide into the clayparticles. Because of the role the particles have to perform i.e.carrying the curing agent for curing the resin impregnating the feltlining material of a tube for lining pipelines and passageways,desireably the particles should be of a relatively small size so thatthey will enter the spaces between the fibres of the felt and bedistributed throughout the felt material in either the wet or dryprocess. In this connection therefore the particles preferably are of asize in the order of 5-15 micron. Larger sized particles can be used butthis means that coarser felt material must be used for the liningmaterial. Where a promoter and catalyst are used the catalyst may beabsorbed in a first group of particles, whilst the promoter may beabsorbed in a second group of particles.

In the first stage of preparation therefore steps were taken toascertain whether or not the Benzoyl Peroxide was being absorbed intothe clay particles when certain mixtures were subjected to ultrasonicenergy. After being subjected to ultrasonic energy to the extent asdescribed hereinafter, the character of the particles in fact changed.

The change was that can be better seen in FIG. 3 which is a photographto an even greater extent of magnification. In FIG. 3! the particlesbecame are shown to be! somewhat flaky and it can be appreciated thatcrevices and pores in the particle are somewhat increased. It is intothese crevices and pores that the curing agent passes as will now beexplained.

The sonification of the clay particles has the effect of reducingparticle size and therefore increasing the surface area of theparticles.

To carry out the test, the clay particles were mixed with BenzoylPeroxide in powder form and Toluene as the solvent for the BenzoylPeroxide.

This mixture was then subjected to ultrasonic energy by the insertion ofan ultrasonic probe running at a power of 60 watts and a frequency of 20kilohertz. The sample comprised 10 grams of Benzoyl Peroxide, 30 gramsof clay and 150 mm of Toluene.

In the first test, the sample was maintained at a temperature of 25° C.,whilst in the second test the temperature was allowed to rise to 60° C.,the same ultrasonic power being applied. To apply the power theultrasonic probe was immersed in the mixture.

In order to provide meaningful results, a comparative test and aweighing test were performed. The comparative test comprised simplymechanically mixing the ingredients in order to ascertain if there wasany take up of Benzoyl Peroxide by involved weighing the particles andliquid phases before and after adsorption.

Firstly, a qualitative set of tests were performed on the resultingmaterials. The first test was to ascertain if the Benzoyl Peroxide hadbeen adsorbed into the clay particles and if so how much. To performthis qualitative test potassium iodide in the form of a 5% solution wasmixed with a 3% standard solution of starch and this mixture was addedto the clay particles after filtering same from the residue of theBenzoyl Peroxide and Toluene. If Benzoyl Peroxide is absorbed and ispresent it will mix with the potassium iodide to turn it to iodine, andthis is indicated by a change from a colourless form to a red form. Thesamples which were subjected to sonification showed this change and thechange took place relatively quickly over a short period in the order of1 minute. The particles from the comparative sample on the other handchanged only to a light red colour over a relatively long period in theorder of 24 hours indicating that not much Benzoyl Peroxide had beentaken up.

Next, qualitative testing was performed using a UV spectrometer.

The clay particles known to have the Benzoyl Peroxide adsorbed thereinfrom the qualitative were mixed with styrene or Toluene as carrier inthe ratio 5 grams of clay particles to 200 ml of carrier and on aliquotportions comparative tests were performed using Beer Lambert Plots whichprovided adsorption and concentration indications. FIG. 2 shows the BeerLambert Plots obtained after the aliquots were respectively subjected tosonication to different extents as indicated by graphs A1 and A2 andalso shown for comparison is graph A3 which represents an aliquot whichwas not subjected to sonication. Graph A3 shows that if the aliquot isnot subjected to sonication there is no desorption of Benzoyl Peroxideat least over the period of the test which was 24 hours.

As regards graph A1 this aliquot was subjected to sonication at 20kilohertz at a temperature held at 25° C. by water circulation and thesonication time was 40 minutes. Noticeable Benzoyl Peroxide desorptionis indicated, but if one refers to graph A2, where no cooling is appliedthere is considerable desorption of the Benzoyl Peroxide even ifsonication takes place only over a relatively short time of 3 minutes.The temperature rise to 60° C. is due to energy up take. These resultsshow therefore that sonication can be used to cause absorption of thecuring agent Benzoyl Peroxide, and equally, when the particles are mixedwith the resin matrix, the curing agent can be caused to desorbselectively from the particles. Clearly use could be made of this inorder to control the time when the resin matrix cures. Controllingwhether or not the Benzoyl Peroxide is absorbed or desorbed whensubjected to sonication is effected by selection of the medium orsolvent in which the Benzoyl Peroxide is contained. There is arelationship between the pore size of the clay particles and themolecular size of the material used for suspending the Benzoyl Peroxideduring adsorption band for desorbing the Benzoyl Peroxide duringdesorption as explained hereinbefore.

Referring to FIGS. 1, B and C, these figures have been included in aneffort to indicate the relieved sequence of events regarding the mannerin which the microporous particles function.

FIG. 1A is a greatly enlarged sectional view of a microporous clayparticle, and it will be seen to comprise a multiplicity of platelets Pwhich are held together by electrostatic attraction. Between theplatelets are micropores or cavities C which receive the resin curingagent which will either be a catalyst or a promoter. It will be assumedfor the purpose of this discussion that the curing agent is the resincatalyst and in particular is Benzoyl Peroxide.

In order to have the microporous particle of FIG. 1A receive thecatalyst in the cavity C, the particle along with all of the others ismixed with a solution comprising Benzoyl Peroxide and Toluene of whichfurther particulars are given hereinafter. The resulting mixture issubjected to ultrasonic energy, and this has the effect of causing theBenzoyl Peroxide to enter the cavity C as shown in cross-hatching inFIG. 1B. The Benzoyl Peroxide is forced into the cavity C by theultrasonic energy, and the particle may undergo a slight expansion.FIGS. 1A and 1B show that the particle is of a size in the order of 7-15micron. The particle in this condition i.e. when it is "filled" with thecuring agent can and does remain quite stable for long periods. This istrue even if the particle is immersed in a resin matrix such as apolyester matrix for which Benzoyl Peroxide is a curing agent. Thecavities are so small that the curing agent does not flow therefrom intothe surrounding matrix to any extent as would cause premature curing. Aresin mixture comprising a matrix and these filled particles cantherefore be employed to impregnate the lining tube at any time selectedby the user. The impregnated lining tube can therefore be stored readyfor use when required. That is to say the curing can be triggered if theBenzoyl Peroxide can be released from the particle cavities C. As willbe appreciated from this specification, this is in fact what issubsequently done, and when the lining tube has been placed in positionon the surface of a passage which it is to line, and a tube is subjectedto energy, that energy is selected so as to cause the particle to expandor in fact disintegrate as shown in FIG. 1C whereby the electrostaticattraction between the platelets P is released or reduced and they openup releasing the Benzoyl Peroxide as indicated by hatching in FIG. 1C.Preferably, the energy used will be ultrasonic energy, but it has beenfound that direct heat can achieve the same effect. It will beunderstood that when ultrasonic energy is used, heat is created in theresin matrix. The result is that the released catalyst causes cure ofthe surrounding resin matrix, and when it is remembered that theseparticles will be distributed throughout the resin, quick and evencuring of the resin is achieved, thereby meeting the installersrequirements for a fully latent resin system.

Applying this technological development to the lining of pipelines andpassageways, it can be seen that the invention provides a means forpreparation of the particles which contain the curing agent, and it isalso established that when these particles are subjected to sonication,the Benzoyl Peroxide can be desorbed into the surrounding matrix wherebyinstallers can now by the use of ultrasonic or other energy control therelease of the curing agent so that curing of the lining tube can beeffected when required and under accurate control. This concept can ofcourse be applied to any system involving the curing of synthetic resin,for example to form articles or to provide fillings for cavities and soon.

Further experiments have suggested that by introducing a sonicneutralizer material further enhanced results concerning the desorbingof the Benzoyl Peroxide can be achieved. One such sonic neutralizermaterial which has been used in tests is the material sodiumhexametaphosphate (SMP) which as shown in FIG. 3 has the effect ofcausing desorbing of the Benzoyl Peroxide at an incredibly fast ratewhen the particles are subjected to sonic energy. In the tests of whichthe results are illustrated by FIG. 3, 0.1 grams of the SMP was mixedwith the clay particles in which the Benzoyl Peroxide was adsorbed aspreviously described, and these were mixed in turn with 200 ml ofstyrene. A first sample was gently swirled. A second sample wassubjected to mechanical stirring, a third sample was subjected tovigorous stirring, and a fourth sample was subjected to sonication at 20kilohertz for 10 seconds. The results are illustrated in FIG. 3 by thegraphs B1, B2, B3 and B4 which are graphs illustrating Benzoyl Peroxidedesorption when examined by a UV spectrometer to provide Beer LambertPlots.

Examining the graphs B1-B4 it can be seen that when the first sample wasgently swirled, there was no desorption of the Benzoyl Peroxide.Mechanical stirring as indicated by graph B2 for 60 minutes indicatesonly a very small amount of Peroxide desorption and there is not muchgreater desorption of the Benzoyl Peroxide when the third sample wasvigorously stirred for 30 minutes.

However, when the fourth sample was subjected to the sonication at 20kilohertz for 10 seconds, the desorption of the Benzoyl Peroxide out ofthe clay is spectacular.

These results indicate that with the addition of a sonic neutralizerwhich we believe has the effect of breaking down the clay particles,desorption becomes extremely efficient and indeed appears to be soefficient that the resin matrix may be utilized without any promoter oraccelerator. It is usual when curing a polyester matrix resin withBenzoyl Peroxide to use an accelerator to assist the cure, but ifdesorption of the Benzoyl Peroxide from the clay particles takes placeunder sonication as efficiently as indicated by graph B4 then suchaccelerator may well be omitted.

As concerns the incorporation of applying the particles in a felt liningtube for a pipelining arrangement as described herein, it hasfurthermore been discovered that if the particles are suspended in anappropriate solution and the lining tube is immersed therein, and thesolution is subjected to sonic energy as indicated above, then theparticles in fact migrate into the felt and impregnate same. The feltsubsequently can be removed and dried to remove liquid so that oneachieves a dry state felt with the particles distributed throughout.This again provides considerable advantage for the pipeline installer,because felts can contain the catalyst ready to receive promotorcontaining particles the resin matrix at the appropriate time. This mayrepresent a considerable advantage because the particles will besubjected to less mechanical stress and shearing forces such as wouldoccur when the particles are mixed with the resin matrix for wet liningoperations.

The present invention therefore provides that resin absorbent materialsmay have distributed therein microporous particles by the use of sonicenergy.

Referring now to FIG. 4, an underground passageway in the form of asewer pipe 10 is being lined by means of a flexible tube 12 suppliedfrom a supply 14 of such tube. The tube is delivered and everted intothe sewer 10 by means of a pump unit 14 which is of the designconstruction and function as set forth in International PatentApplication PCT/GB91/01603 and U.S. Pat. No. 5,154,936. This unit 14serves to pump and evert the tube 12 as shown in FIG. 4. A leading end16 of the tube may be anchored to the outlet of the unit 15.

The right hand portion of FIG. 4 shows the tube 12 fully positioned andit is illustrated as having a closed trailing end 18. To said end 18there may be attached a hold back rope, cable or the like in order toprevent the rope 18 from rupturing under the eversion pressure.

A specific application of use of the microporous particles in connectionwith pipe lining operations will now be described with reference toFIGS. 4 to 6.

It is convenient now to refer to FIG. 5 which shows the lining tube 12in greater detail. Tube 12 will be seen to comprise a core section 20which is made up of one or more layers of an absorbent material such asa fibrous felt or woven fabric or a combination of these materials orother suitable absorbent materials, and surrounding layer 20 is animpermeable layer 22 which typically in the case of the layer 20 beingof polyester felt is of polyurethene film which is bonded to the outerlayer of the felt 20.

The felt 20 in practise is impregnated with a curable synthetic resin,and also contained in the resin matrix are the microporous materialparticles as described herein which contain curing agent for the resin,said particles being indicated by reference 24 and being shown inenlarged scale for clarity. These particles will be much smaller e.g. inthe order of 5-15 micron, and will be distributed throughout the resinmatrix.

In the arrangement of FIG. 5, the tube 12 is shown in its manufacturedcondition i.e. before application to the sewer surface, and it will beunderstood that when the tube 12 is everted as shown in FIG. 4, theouter skin or membrane 22 will eventually lie to the inside of theapplied tube. This is illustrated more particularly in FIG. 6 whichshows the tube 12 in the process of eversion. A portion 12A has beeneverted, and the felt surface soaked with resin is turned outwardlywhilst the membrane 22 is to the inside, whilst the portion 12B is theinwardly travelling portion, in that it moves in the direction of arrow26 during eversion.

The resin remains uncured until the lining is subjected to energy inthis case sonic energy to cause the curing agent to desorb as describedhereinbefore. Sonic energy may be applied at one or more locations byultrasonic generators for example at location 30 which is ahead of thepump unit 15, 32 on the inwardly travelling portion 12B of the liningtube or at 34 which shows that the sonic energy is applied to the liningtube after it has been everted on to the surface of the sewer 10. As analternative to the sonic generator in the pipeline, heat can be appliedby hot water which is circulated through the lining tube after it hasbeen applied to the passageway surface. With the application of sonicenergy (and heat when applied) the curing agent desorbs from theadsorbent particles and commences and effects the cure of the resinmatrix. By this means, the start of curing can be controlled and thecuring time can be substantially reduced.

The sonic generator as shown in FIG. 5 is designed to apply sonic energyto the lining tube 12 in that the generator applies energy as indicatedby arrows 36 on the membrane surface 22. This energy as described hereinreleases the catalyst and/or promoter into the resin matrix initiatingand/or effecting the cure and therefore this method has all theadvantages of delayed and selective curing so that lining tubes can bepre-impregnated with the resin matrix and microporous particlesadsorbent materials and stored until ready for installation which is aconsiderable advantage.

The microporous particles can be produced by any known means and can beused on their own or in conjunction with ferrite particles ashereinbefore described.

It is to be mentioned at this time that the materials which are used forthe lining tube may be as described in the said U.K. Patents 1,340,068and 1,449,445 to which reference is also made.

The dry impregnation method can be used for impregnation of the feltwith the filled microporous particles and this may be achieved bypassing the felt through a suspension bath containing the particles insuspension and which is subjected to sonication of appropriatewavelength and energy.

The invention utilizes ultrasonic energy with particular advantage in anumber of aspects.

Firstly, ultrasonic energy is used for causing the catalyst/promoter tobe adsorbed into the microporous particles.

Secondly, sonic energy is used in the curing stage for causing desorbingof the curing agent from the particles. In this connection the resinmatrix may include a sonic neutralizer such as SHP, and by the use ofsonic energy to desorb the curing agent, efficient control over thecuring time cycle may be achieved. Control of the cure of the liningtube may therefore be effected efficiently. The cure of the lining tubemay be effected initially above ground as illustrated in the drawings,and may be continued if necessary after the lining tube has been placedin position on the pipeline or passageway. Alternatively, the curing maybe effected after the lining tube has been placed in position by using asonic generator inside the pipe. This method may be particularlyefficient if the resin includes the SXP because cure can be effected ina remarkably short time, which has considerable advantage.

Thirdly, sonic energy can be used for impregnating the felt with theparticles in the dry method, although the particles will be contained ina liquid suspension through which the felt is passed, and which issubjected to sonication in order to provide for take up of theparticles. The felt subsequently will be dried to remove the liquidphase, and then the resulting impregnated felt can be furtherimpregnated with the resin matrix as and when required.

The invention extends to these individual aspects singly or incombination. It applies generally to the field of impregnation ofmaterials, and also specifically to the particular application of liningunderground passageways and the various aspects thereof.

As to the sonic generator which is used in any particular application,it is preferred that a resonating generator, as described in U.S. Pat.No. 5,200,666 used as a single unit or as a double unit in order toachieve amplified sonic energy application, be used. The ultrasonicgenerators will be arranged in pairs for example as defining nip rollsthrough which the lining tube is passed in the specific application ofthe invention to the lining of pipelines and passageways. Sonic energymay be applied in a number of stages each comprising a pair ofgenerators in the form of nip rolls arranged at spaced intervals in thedirection in which the lining tube passes. Any sonic generator asappropriate may be adopted including RUM methods.

It has been mentioned herein that in the absorbing and desorbing of thecuring agent, absorbing and desorbing is achieved depending upon the useof the solvent in which the particles are contained. In the case ofabsorbing of the curing agent, this is achieved by using a solvent of asimilar molecular size to that of the curing agent e.g. Benzoyl Peroxideand Toluene, and Benzoyl Peroxide and Toluene are absorbed in the sameratio. When it is desired however to desorb the Benzoyl Peroxide when itis subjected to sonic energy, the particles should be contained in asolvent which has a smaller molecular size than the Benzoyl Peroxide sothat it will displace the Benzoyl Peroxide to desorb same.

The sonic neutralizer SMP which is referred herein is one of a number ofmaterials which act to break down clay under sonic energy. It isbelieved to be an ionic neutralizer.

As to the step of subjecting the particles to sonication for absorbingof the Benzoyl Peroxide, tests have shown that up to 60% by weight ofBenzoyl Peroxide can be adsorbed into the clay particles after 20minutes sonication and 30% by weight can be adsorbed after 10 minutessonication, and these figures take into account any Benzoyl Peroxidethat may be removed following washing of the absorbent particles.

When the lining tube impregnated with the resin and including theparticles is subjected to ultrasound, the ultrasound may have the effectof heating the tube which in turn has the effect of causing desorbing ofthe Benzoyl Peroxide.

An advantage of the use of ultrasonics as referred to herein means thatthe lining tubes can be manufactured with conventionally used materialsand using conventionally used resin systems. It may be necessary toapply a secondary coating to the particles in which the Benzoyl Peroxideis adsorbed in order to limit desorption until specifically required.

It has been further discovered that desorption of the curing agent canbe achieved in any embodiment of the invention if the adsorbentparticles can be heated. The heat it is believed has the effect ofexpanding the particles or at least the pores thereof as describedherein causing the retained curing agent to desorb into the surroundingresin matrix. This happens even when the microporous particles arecoated for the retention of the curing agent; the coating breaks due tothe particle expansion and/or melts under the heating action.

A particularly advantageous release of the curing agent from theadsorbent particles therefore is achieved if the resin matrix containsmagnetically permeable particles such as ferrites in which heat can begenerated by creating eddy currents and hysteresis losses in theparticles. According to a preferred arrangement of the inventiontherefore the resin matrix in addition to the adsorbent particlescontains particles such as ferrites (for example as indicated at F inFIG. 1A) which can be heated when subjected to an alternating magneticfield, and such a field is applied to the resin material preferably whencontained in the lining tube in order to heat the particles to providethe desorbing of the resin and curing of the same. A particularadvantage is obtained if the magnetically permeable particles areferrites having a CURIE temperature of a value for example of 80° C. to150° C. which limits the extent to which the ferrite is heated so thatthe particles do not become excessively hot, by which is meant that theparticles do not burn the resin or the material impregnated thereby.

Any suitable means of providing the alternating magnetic field may beprovided, although the machine set forth in UK patent application No9409014.9 is preferred. The alternating magnetic field may be applied atany one or more of the locations 30, 32 and 34 (FIG. 5) and may be inaddition to or in place of the ultrasonic energy.

Again, it is to be mentioned that heat can be generated in the resinmatrix by using conductive particles and by applying an alternatingelectric field or by creating electric currents using resistance heatingby applying an electric potential across the resin matrix material.

The magnetically permeable particles and/or the conductive particles maybe contained in the resin and/or in the microporous particles.

I claim:
 1. A flexible lining tube (12) for cured in place lining ofpipelines and passageways (10) comprising, a resin absorbent materiallayer (20) which is impregnated with a curable synthetic resincontaining microporous particulate material (24) distributed therein,said microporous particulate material (24) having a curing agent for theresin retained in the pores preventing curing of the resin until thecuring agent is released by the application of energy thereto enablingthe lining tube to be stored and used when required.
 2. The lining tubeof claim 1, wherein the microporous particular material (24) is a clay.3. The lining tube of claim 1, wherein the synthetic resin includesmagnetically permeable particles dispersed therein.
 4. The lining tubeof claim 1, wherein the magnetically permeable particles are in theresin matrix by being embodied in the microporous particles (24).
 5. Theflexible lining tube of claim 1, wherein said curing agent includes acatalyst for the resin.
 6. The flexible lining tube of claim 1, whereinsaid curing agent includes an accelerator for the resin.
 7. The flexiblelining tube of claim 1, wherein the microporous particles (24) are in afirst and a second group and the curing agent includes a catalyst in thefirst group of the microporous particles (24) and an accelerator in thesecond group of the microporous particles (24).
 8. The lining tube ofclaim 7, wherein that said first group of particles (24) are of clay ofa first type and the said second group of particles (24) are of a clayof a second type.
 9. The lining tube of claim 1, wherein said absorbentlayer (20) is of a fibrous felt.
 10. The lining tube of claim 1, whereinthe lining tube (12) has an outer layer (22) in the form of a coating orfilm of impermeable material.
 11. A method of rendering flexible liningtube (12) having an absorbent layer (20) suitable for lining anunderground pipeline or passageway, comprising disposing throughout theabsorbent layer microporous particles (24) having a resin curing agentin the pores thereof by bringing the microporous particles (24) andabsorbent layer (2) into close proximity and subjecting the layer (20)and particles (24) to sonic energy to cause the particles to migrateinto the absorbent layer (20).
 12. The method of claim 11, includingcarrying the particles (24) in a liquid in suspension and immersing thelining tube (12) in the suspension, the whole being subjected to sonicenergy.
 13. The method of claim 11, including applying the sonic energyby means of an ultrasonic probe and plate or pair of such probes orplates.
 14. A method of lining a pipeline or passageway (10) using aflexible lining tube (12) having a resin absorbent layer (20)impregnated with a curable resin matrix including first particles (2)containing curing agent for the resin, and selectively releasabletherefrom by the application of energy comprising,(a) applying thelining tube (12) to the surface of the passageway (10) or inner surfaceof the pipeline (10) by fluid pressure whilst the lining tube (12) isflexible, (b) applying energy to the tube (12) so that curing agent isreleased from the resin matrix and cures the resin as the tube (12) isso held against the said surface, (c) wherein the first particles (24)are microporous and the curing agent is contained in the pores thereofand the resin contains second and magnetically permeable particles andthe energy applied comprises an alternating magnetic field, and (d)whereby the magnetically permeable particles are heated which in turncauses desorbing of the curing agent from said microporous particles(24).
 15. The method of claim 14, including selecting magneticallypermeable particles that are ferrites having a CURIE temperatureselected not to damage the resin or the absorbent material (20).
 16. Themethod of claim 15, wherein the CURIE temperature of the magneticallypermeable particles (24) is in the range of 80° to 150° C.